Definir : que son las lineas imaginarias? ¿Que me permiten realizar?

If we review the changes in the landscape surrounding the great salt lake in utah we can see a change in topography. look at the area to the south of the lake. what changes occurred during the last twenty-nine years? a-erosion of the hills b-an increase in marshland c-flooding of the area and the development of wetlands d-deposition of sediments and an increase in elevation